CN107994301A - A kind of light charging secondary cell using heteropolyacid salt as negative material - Google Patents

Abstract

A photorechargeable secondary battery using a heteropoly acid salt as a negative electrode material, comprising a photoanode (1), a positive electrode (2), a negative electrode (3), and a lithium ion conductor film (4). The negative electrode material is mixed with a nano-heteropolyacid salt material, a conductive agent and a binder according to a certain mass ratio, added to a dispersant, fully stirred to make the mixture uniform, coated and dried to form an electrode sheet. The preparation of the nanometer heteropolyacid acid salt material in the present invention includes mixing the inorganic salt solution and the heteropolyacid aqueous solution to obtain the solid phase nanometer heteropolyacid acid salt material and the preparation of the electrode material. The heteropoly acid salt adopted in the invention has diversity in structure and composition, high thermal stability, photoreducibility, and can carry out reversible and continuous multi-electron redox. The light-rechargeable secondary battery prepared by the method of the invention can be charged under light conditions, fully utilizes solar energy, saves charging energy, and has low cost and simple equipment.

Description

A photorechargeable secondary battery using heteropoly acid salt as negative electrode material

technical field

The invention relates to a photorechargeable secondary battery using heteropolyacid salt as a negative electrode material, and belongs to the technical field of photoelectrochemical batteries.

Background technique

The development of clean and renewable energy is an effective way to solve problems such as global warming and energy crisis. Solar energy has the advantages of being clean, renewable, and rich in resource reserves, and is considered to be the most effective alternative to fossil energy. However, affected by the length of sunshine duration and large changes in intensity, solar energy needs to be converted and stored into electrical energy that can be output stably before it can be effectively utilized by humans. A photorechargeable secondary battery is an energy conversion and storage device that can directly convert solar energy into chemical energy and electrical energy. The battery combines the photoelectric conversion function of the photoelectrochemical cell, draws on the energy storage principle of the secondary battery, has the characteristics of photoelectric energy conversion, rechargeability and stable electric energy output, and provides a new idea for the large-scale storage and utilization of solar energy. .

At present, the storage capacity of light-rechargeable secondary batteries is far lower than that of traditional secondary batteries such as nickel metal hydride and lead-acid batteries, and its performance cannot meet the requirements of battery applications and cannot meet the large-scale storage of solar energy. In the photorechargeable secondary battery, the rate at which the photocathode material accepts and stores photogenerated electrons plays a crucial role in the photoelectrochemical energy conversion efficiency of the photochargeable secondary battery. Therefore, the development of new anode materials with high energy level matching, good conductivity, and large charge-discharge specific capacity is of great significance for improving the photoelectrochemical energy conversion efficiency and storage capacity of photorechargeable secondary batteries.

As a multifunctional material, heteropolyacid salt (AnXM ₁₂ O ₄₀ ) has been widely used in photochromic, electrochromic, and energy storage materials. Heteropolyacids have structural and compositional diversity, high thermal stability, photoreducibility, reversible and continuous multi-electron redox, and have the ability to transport and store electrons and protons. Heteropolyacid anions can carry out a series of fast reversible reduction processes of one electron and two electrons, and have a certain storage capacity for photogenerated electrons. The negative electrode material of the secondary battery provides a stable structure during the charge-discharge cycle process.

Contents of the invention

The object of the present invention is to propose a method for preparing a nano-heteropolyacid salt as the negative electrode material in order to solve some defects in the photorechargeable secondary battery.

Realize the technical scheme of the present invention as follows:

A photorechargeable secondary battery using heteropolyacid salt as a negative electrode material, including a photoanode, a positive electrode, a negative electrode, and a diaphragm. The positive electrode is lithium iodide, and the diaphragm is a lithium ion conductor film; the negative electrode material is mixed with a nano-heteropoly-salt material, a conductive agent and a binder according to a certain mass ratio; the nano-heteropoly-salt The mass ratio of material to conductive agent and binder is (6~8):(1~3):1.

The nano heteropoly acid salt is _An XM ₁₂ O ₄₀ , wherein A is a rare earth element, NH ₄ , K, Rb, Ag or Cu; X is P or Si; M is W or Mo.

The photoanode is a dye-sensitized titanium dioxide, tin dioxide or zinc dioxide electrode.

The lithium ion conductor film is a nafion film or a LiSICON film.

A method for preparing a nanometer heteropolysalt negative electrode material, the steps are as follows:

(1) Synthesis of nano-heteropolyacid salt material: mix inorganic salt solution and heteropolyacid aqueous solution, react at a certain temperature and stirring speed, and react for a certain period of time. After the reaction is completed, cool, filter, wash, and dry , to obtain solid-phase nano-heteropolyacid materials.

(2) Preparation of electrode materials: Disperse the nano-heteropolysalt material, conductive agent, and binder into the solvent, stir evenly to form a slurry, coat it on the current collector, dry it, and set it aside.

The current collector is one of conductive glass, metal titanium, conductive paper, and flexible conductive material, and the vacuum drying condition is 50-80°C.

When synthesizing the nano-heteropolyacid salt material, the reaction temperature is 40-60°C, the reaction stirring speed is 300-600r/min, and the reaction time is 6h-12h.

The conductive agent is one or more of acetylene black, carbon nanotubes, graphene, Super P, KB, VGCF; the binder is one of an organic binder or a water-based binder; the solvent is N -Methylpyrrolidone (NMP) or deionized water.

The beneficial effect of the present invention is that the nano-heteropolyacid salt material ( _An XM ₁₂ O ₄₀ ) synthesized by the present invention has diversity in structure and composition, high thermal stability, and can carry out reversible and continuous multi-electron oxidation Reduction, has the ability to transport and store electrons and protons, and provides a stable structure for the charge-discharge cycle process of the negative electrode material of the photorechargeable secondary battery. The nanometer heteropolyacid salt material ( _An XM ₁₂ O ₄₀ ) synthesized by the invention effectively improves the cycle life of the photochargeable secondary battery.

The heteropoly acid salt negative electrode material involved in the invention has simple preparation process, safe reaction conditions, simple and convenient operation, and the reagents involved in the reaction are less harmful to the environment. Applicable to large-scale production.

Description of drawings

Fig. 1 is a schematic diagram of the battery structure of the present invention;

In the figure, 1 is the photoanode; 2 is the positive electrode; 3 is the cathode; 4 is the lithium ion conductor film;

Fig. 2 is the transmission electron microscope figure that adopts the nanometer ammonium phosphotungstate material made in embodiment 1;

Fig. 3 is the voltage-time curve when adopting the nano-ammonium phosphotungstate negative electrode material made in Example 1 to be 10min when the photocharging time is 50mA/g when the discharge current density is;

Fig. 4 is the discharge capacity-cycle life curve when the light charging time is 10min and the discharge current density is 50mA/g using the nanometer ammonium phosphotungstate negative electrode material prepared in Example 1;

Fig. 5 adopts the nano-ammonium phosphomolybdate negative electrode material made in embodiment 2 to be 20min at the photocharging time, and the voltage-time curve when the discharge current density is 75mA/g;

Fig. 6 adopts the nano-ammonium phosphomolybdate negative electrode material made in embodiment 2 to be 20min at the photocharging time, and the discharge capacity-cycle life curve when the discharge current density is 75mA/g;

Fig. 7 is the voltage-time curve when adopting embodiment 3 nano-potassium silicotungstate negative electrode material to be 30min in photocharging time, discharge current density when being 50mA/g;

Fig. 8 is the discharge capacity-cycle life curve of the nano-potassium silicotungstate negative electrode material prepared in Example 3 when the photocharging time is 30 min and the discharge current density is 50 mA/g.

Detailed ways

The structure of a light-rechargeable secondary battery using heteropolyacid salt as the negative electrode material in this embodiment is shown in FIG. 1 . It includes photoanode 1, positive electrode 2, negative electrode 3 and lithium ion conductor film 4. The positive electrode is lithium iodide; the lithium ion conductor film is wrapped on the outer surface of the cathode; the negative electrode material is mixed with a nanometer heteropolyacid salt material, a conductive agent and a binder according to a certain mass ratio; the nanometer heteropolyacid The mass ratio of the salt material to the conductive agent and the binder is (6~8):(1~3):1; the positive electrode is located between the photoanode and the negative electrode.

Example 1

Preparation of nano ammonium phosphotungstate negative electrode material and electrode sheet:

(1) Preparation of nano ammonium phosphotungstate: take 25ml, 0.19mol/L ammonium chloride solution, slowly add the ammonium chloride solution into 50ml, 0.09mol/L phosphotungstic acid solution, and the reaction temperature is 40℃ , Magnetic stirring speed 550r/min. The reaction time is 8h. Cool to room temperature after the reaction, wash and dry. Potassium phosphotungstate was prepared with nanometer microspheres. Its transmission electron microscope picture is shown in Figure 2.

(2) Mix the nano-ammonium phosphotungstate material prepared above, acetylene black and PVDF according to the weight ratio of 7:2:1, N-methylpyrrolidone is used as the dispersant, stir well to make the mixture uniform, and roll it into a sheet. Vacuum dry at 80°C for 12 hours for later use.

(3) Use the lithium iodide propylene carbonate solution prepared above as the negative electrode, the titanium dioxide as the photoanode, and the electrolyte solution as 0.1 mol/L, and assemble it into a battery in a glove box. The voltage-time curve when the photocharging time is 10min and the discharge current density is 50mA/g is shown in Figure 3. The discharge capacity-cycle life curve of the prepared nano-ammonium phosphotungstate negative electrode material is shown in Figure 4 when the light charging time is 10 minutes and the discharge current density is 50mA/g.

Example 2

Preparation of nano ammonium phosphomolybdate negative electrode material and electrode sheet:

Replace the phosphotungstic acid solution in step (1) in Example 1 with phosphomolybdic acid solution, and replace the reaction time of step (1) in Example 1 from 8h to 6h. In the step (2) of Example 1, nano-ammonium phosphotungstate was replaced with nano-ammonium phosphomolybdate, and the others were the same as in Example 1. The voltage-time curve when the photocharging time is 20min and the discharge current density is 75mA/g is shown in Fig. 5 . The discharge capacity-cycle life curve of the prepared nano-ammonium phosphotungstate negative electrode material is shown in Figure 6 when the light charging time is 20min and the discharge current density is 75mA/g.

Example 3

Preparation of nano-potassium silicotungstate material:

Replace the ammonium chloride solution in step (1) in Example 1 with potassium chloride solution, replace the phosphotungstic acid solution in step (1) in Example 1 with silicotungstic acid solution, and replace the solution in step (1) in Example 1 with In (1) the reaction temperature is replaced from 40°C to 60°C, and the reaction time in (1) in Example 1 is replaced from 8h to 4h. In the step (2) of Example 1, nano ammonium phosphotungstate was replaced by nanometer potassium silicotungstate, and the others were the same as in Example 1. The voltage-time curve when the photocharging time is 30min and the discharge current density is 50mA/g is shown in Fig. 7 . The discharge capacity-cycle life curve of the prepared nano-potassium silicotungstate negative electrode material is shown in Figure 8 when the light charging time is 30min and the discharge current density is 50mA/g.

Claims (8)

1. The secondary cell 1. a kind of light using heteropolyacid salt as negative material charges, including light anode, cathode, anode, membrane, it is special Sign is that described just extremely lithium iodide, membrane are lithium ion conductor film；The negative material by nanometer heteropolyacid salt material, lead Electric agent and binding agent are mixed according to certain mass ratio；The nanometer heteropolyacid salt material and conductive agent, the matter of binding agent Measuring ratio is（6~8）:（1~3）:1.
2. The secondary cell 2. a kind of light using heteropolyacid salt as negative material according to claim 1 charges, it is characterised in that The nanometer heteropolyacid salt is A_nXM₁₂O₄₀, wherein A is rare earth element, NH₄, K, Rb, Ag or Cu；X is P or Si；M is W or Mo.
3. The secondary cell 3. a kind of light using heteropolyacid salt as negative material according to claim 1 charges, it is characterised in that The light anode is titanium dioxide, stannic oxide or the zinc oxide electrode of dye sensitization.
4. The secondary cell 4. a kind of light using heteropolyacid salt as negative material according to claim 1 charges, it is characterised in that The lithium ion conductor film is nafion films or LiSICON films.
5. The secondary cell 5. a kind of light using heteropolyacid salt as negative material according to claim 2 charges, it is characterised in that The preparation method of the nanometer heteropolyacid salt：

   （1）The synthesis of nanometer heteropolyacid salt negative material：Inorganic salt solution is mixed with heteropoly acid aqueous solution, in a constant temperature Reacted under the conditions of degree and mixing speed, react certain time, after the completion of reaction, cooling, filtering, washing, drying, obtain solid phase and receive Rice heteropolyacid salt material；

   （2）The preparation of electrode material：Nanometer heteropolyacid salt negative material, conductive agent, binding agent are distributed in solvent, and stirring is equal It is even, slurry is formed, is coated on collector, after drying.
6. The secondary cell 6. a kind of light using heteropolyacid salt as negative material according to claim 5 charges, it is characterised in that The collector is electro-conductive glass, one kind in Titanium, conductive paper, flexible conducting material, and vacuum drying condition is 50-80 ℃。
7. The secondary cell 7. a kind of light using heteropolyacid salt as negative material according to claim 5 charges, it is characterised in that During the nanometer heteropolyacid salt materials synthesis, reaction temperature is 40-60 DEG C, and reaction mixing speed is 300-600r/min, reaction Time is 6h-12h.
8. The secondary cell 8. a kind of light using heteropolyacid salt as negative material according to claim 5 charges, it is characterised in that The conductive agent is the one or more in acetylene black, carbon nanotubes, graphene, Super P, KB, VGCF；Binding agent is organic One kind in binding agent or aqueous binders；Solvent is 1-methyl-2-pyrrolidinone（NMP）Or deionized water.